This invention relates in general to mountings for the road wheels of automotive vehicles, and more particularly to wheel mountings that have the capacity to transfer pressurized air to or from the pneumatic tires as the wheels rotate.
The typical automotive vehicle rides on pneumatic tires mounted on metal rims, with the tires and rims forming the road wheels for the vehicle. The rims are in turn bolted to some type of hub which turn on bearings. Typically, the tires are inflated to a pressure specified by the manufacturer, and left at that pressure. Many individuals virtually ignore the tires, checking the pressure in them at only infrequent intervals, which is indeed a dangerous practice.
Not all driving conditions demand the same inflation pressure for the tires on a vehicle. Obviously, high speed highway driving requires greater pressure than low speed driving in congested urban areas where the tires, by virtue of the lower speeds, are not likely to reach elevated temperatures. This is convenient because urban streets are often rougher than highways, so lower tire pressures enable the tires to absorb impacts that would be transferred to the vehicle chassis at higher pressures. Similarly, so-called off road vehicles, such as those used by the military, are expected to operate on a wide variety of terrain, as well as on paved road surfaces. But much of the off road terrain requires greater traction than paved roadways, and this increased traction can be derived through a reduction in tire pressure. But this requires releasing air from the tires on a multiwheeled vehicle, which is time consuming and often of little avail once the wheels becomes mired in mud or sand. Just as significant, when the vehicle again comes to a paved surface, its tires must carry enough pressure to operate on such a surface at reasonable speeds. If the tire has been deflated to increase traction, it again needs to be inflated, but facilities for inflating tires are not always nearby. Even a vehicle that operates totally on paved surfaces, may encounter conditions where increased traction is desirable, such as snow and ice, or even a rain-slickened street, traction that could be obtained simply by reducing the pressure of the air in its tires, but most drivers are reluctant to undertake the procedures to release air, particularly in inclement weather.
Wheel mountings exist for automotive vehicles, or have at least been disclosed, which place the tires of road wheels in communication with central air reservoirs on such vehicles where the air is maintained under pressure. The wheel mountings utilize bearings organized in pairs and in opposition, and those mountings transmit the air through the spaces between the bearings of each pair. The bearings require special seals to prevent the pressurized air from flushing their lubricants into the tires or air reservoir.
The present invention resides in a mounting including a hub and a spindle as well as bearings located between the hub and spindle. A sealed chamber exists at the end of the spindle and remote from the bearings, it being isolated from the bearings by a live seal. A passageway extends along the spindle to the sealed chamber and another extends from the hub to the chamber, thus enabling pressurized air to be transmitted through the mounting while the hub rotates.